Toolbelt - Last-used slot

[doppelEben]

TL;DR

Would be nice if there would be an option that I can set a slot in the toolbelt to automatically show the last item I held in hand.

What ?

Set any slot of the toolbelt to "last-used-item" - like in the older factorio versions, if a slot was free, the held item dropped into the toolbelt automatically and not the inventory. Like I set a filter f.E. assembling machines, I can set it to "last-used", or "last-held".

Why ?

Would be nice if one can use a slot as "last used". f.E. I don't want "labs" in the toolbelt directly, and am building my lab-street, I switch probably switch between severall items, such as electric poles (in toolbelt), belts (in toolbelt) and inserters (in toolbelt too). But then I build also labs - and in the old version, 0.16 (I guess) the lab would be dropped into the toolbelt if there is a free slot. But now I have to open the inventory every time I want to build another lab after/between belts/inserters, or want to move one/rebuild, since the labs dont go into the toolbelt anymore, if I dont use a slot for the labs exclusively. So is it possible to make something like: "slot XY, show me always the last item I had in hand?"